1. Field of the Invention
The present invention relates to ad serving systems of the type that serve ads for display on web pages. More particularly, the invention relates to computer-implemented methods for reducing fraudulent uses of such ad serving systems.
2. Description of the Related Art
Online advertising has seen tremendous growth, and it is now a multi-billion dollar industry. Many companies provide online ad placement services on a “cost per click” (or CPC) basis. With this model, an advertiser pays the provider of an ad placement service a small amount, such as 10¢, every time a user clicks on an ad. Typically, the ad placement service is capable of serving ads for display on the web pages of a number of different participating web sites. The resulting revenue collected from the advertisers is typically shared between the operators of these participating web sites (referred to as ad “publishers”) and the ad placement service provider.
As cost-per-click advertising has increased in popularity, various forms of fraudulent activity or “click fraud” have become common. For example, an unscrupulous entity may repeatedly click on the ads of a competitor in an effort to deplete the competitor's advertising budget. As another example, a web site owner may click on the ads placed on its own web site to generate revenue. In both of these examples, the entity engaging in click fraud may write a program that automates the task of clicking on the ads, or may pay an outside individual to click on the ads.